Re: tableam vs. TOAST

On Thu, 7 Nov 2019 at 22:45, Ashutosh Sharma <ashu(dot)coek88(at)gmail(dot)com> wrote:

> On Thu, Nov 7, 2019 at 7:35 PM Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> >
> > On Thu, Nov 7, 2019 at 1:15 AM Ashutosh Sharma <ashu(dot)coek88(at)gmail(dot)com>
> wrote:
> > > @Robert, Myself and Prabhat have tried running the test-cases that
> > > caused the checkpointer process to crash earlier multiple times but we
> > > are not able to reproduce it both with and without the patch. However,
> > > from the stack trace shared earlier by Prabhat, it is clear that the
> > > checkpointer process panicked due to fsync failure. But, there is no
> > > further data to know the exact reason for the fsync failure. From the
> > > code of checkpointer process (basically the function to process fsync
> > > requests) it is understood that, the checkpointer process can PANIC
> > > due to one of the following two reasons.
> >
> > Oh, I didn't realize this was a panic due to an fsync() failure when I
> > looked at the stack trace before. I think it's concerning that
> > fsync() failed on Prabhat's machine, and it would be interesting to
> > know why that happened, but I don't see how this patch could possibly
> > *cause* fsync() to fail, so I think we can say that whatever is
> > happening on his machine is unrelated to this patch -- and probably
> > also unrelated to PostgreSQL.
> >
>
> That's right and that's exactly what I mentioned in my conclusion too.
>
>
In fact, I suspect this is PostgreSQL successfully protecting itself from
an unsafe situation.

Does the host have thin-provisioned storage? lvmthin, thin-provisioned SAN,
etc?

Is the DB on NFS?

--
Craig Ringer http://www.2ndQuadrant.com/
2ndQuadrant - PostgreSQL Solutions for the Enterprise